A mouse is used to position a cursor on a computer screen and to give various commands to the computer.
Currently, the most common mouse is an electronic type. However, an optical mouse is also available.
JP 09190277 discloses an optical mouse which has a CCD line sensor for the X-axis and a CCD line sensor for the Y-axis. Data which is recorded by the CCD line sensors at a particular time is compared with data which is recorded at a subsequent time, by means of which the movement of the mouse in the X- and Y-direction can be determined.
U.S. Pat. No. 4,814,553 discloses a similar optical mouse which can determine its absolute position on a mouse pad which is provided with a specific line pattern.
The combination of a mouse function and an input function in an input unit is also known from, for instance, U.S. Pat. No. 4,804,949, WO00/08593 and U.S. Pat. No. 5,932,863. A further example of this is shown in the Applicant's International Patent Publication WO99/60468. This describes an input unit comprising an image-recording device for recording images and an image processing device for processing the images to achieve the input function and the mouse function. The mouse function is more specifically based on the determination of the relative positions of images recorded in succession.
It is a general requirement that a mouse or other input unit is to be able to carry out as many functions as possible and be used by the user in as flexible and simple a way as possible.